<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>GSAP 布局切换</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: Arial, sans-serif;
            background: linear-gradient(135deg, hsl(200, 60%, 85%), hsl(340, 70%, 85%));
            height: 100vh;
            overflow: hidden;
            display: flex;
            flex-direction: column;
        }

        /* Header */
        .header {
            height: 60px;
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(10px);
            border-bottom: 1px solid rgba(0, 0, 0, 0.1);
            display: flex;
            align-items: center;
            padding: 0 20px;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
            position: relative;
            z-index: 20;
        }

        .header .logo {
            font-size: 20px;
            font-weight: bold;
            color: #333;
        }

        .header .switch-button {
            background: #007bff;
            color: white;
            border: none;
            padding: 10px 20px;
            border-radius: 5px;
            cursor: pointer;
            margin-left: auto;
            z-index: 30;
        }

        /* 主容器 */
        .main-container {
            flex: 1;
            display: flex;
            overflow: hidden;
        }

        /* 经典布局：Sidebar */
        .sidebar {
            width: 250px;
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(10px);
            border-right: 1px solid rgba(0, 0, 0, 0.1);
            padding: 20px;
            overflow-y: auto;
        }

        .sidebar ul {
            list-style: none;
        }

        .sidebar ul li {
            margin-bottom: 15px;
            padding: 10px;
            border-radius: 5px;
            cursor: pointer;
            transition: background 0.3s ease;
        }

        .sidebar ul li:hover {
            background: rgba(0, 0, 0, 0.1);
        }

        /* 内容区域 */
        .content {
            flex: 1;
            padding: 20px;
            overflow-y: auto;
            background: rgba(255, 255, 255, 0.8);
            backdrop-filter: blur(10px);
            min-width: 0; /* 允许宽度压缩 */
        }

        /* 单页布局：Header 菜单 */
        .spa-header .menu {
            display: flex;
            gap: 20px;
            position: absolute;
            left: 50%;
            top: 50%;
            transform: translate(-50%, -50%);
            opacity: 0;
        }

        .spa-header .menu a {
            text-decoration: none;
            color: #333;
            font-weight: bold;
            padding: 10px;
            border-radius: 5px;
        }
    </style>
</head>
<body>
<!-- Header -->
<div class="header" id="header">
    <div class="logo">LOGO</div>
    <button class="switch-button" id="switchButton">切换到单页布局</button>
</div>

<!-- Main Container -->
<div class="main-container is-classic" id="mainContainer">
    <div class="sidebar" id="sidebar">
        <ul>
            <li><a href="#">仪表盘</a></li>
            <li><a href="#">用户管理</a></li>
            <li><a href="#">设置</a></li>
            <li><a href="#">退出登录</a></li>
        </ul>
    </div>
    <div class="content">
        <h1>内容区域</h1>
        <p>这是内容区域。</p>
    </div>
</div>

<!-- 引入 GSAP -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/3.12.2/gsap.min.js"></script>
<script>
    const switchButton = document.getElementById('switchButton');
    const mainContainer = document.getElementById('mainContainer');
    const sidebar = document.getElementById('sidebar');
    const header = document.getElementById('header');
    const content = document.querySelector('.content');
    let isClassic = true;

    // 初始化时间线
    const tl = gsap.timeline({paused: true});

    // 配置动画
    tl.to(sidebar, {
        x: -250, // 向左移动 250px
        duration: 0.5,
        ease: "power2.inOut"
    })
        .to(content, {
            x: -250, // 同步向左移动
            width: "100%", // 直接设置宽度为 100%
            duration: 0.5,
            ease: "power2.inOut"
        }, "<") // 与上一个动画同步开始
        .add(() => {
            // 动画完成后移动菜单到 Header
            const menu = sidebar.querySelector('ul');
            menu.style.opacity = 0;
            header.appendChild(menu);
            header.classList.add('spa-header');
            gsap.to(menu, {opacity: 1, duration: 0.3});
        });

    // 切换布局
    switchButton.addEventListener('click', () => {
        if (isClassic) {
            tl.play();
            switchButton.textContent = '切换到经典布局';
        } else {
            // 反向动画：先将内容区域向右移动，再展开 Sidebar
            tl.reverse();
            switchButton.textContent = '切换到单页布局';

            // 反向动画完成后移回菜单
            tl.eventCallback("onReverseComplete", () => {
                const menu = header.querySelector('ul');
                menu.style.opacity = 0;
                sidebar.appendChild(menu);
                header.classList.remove('spa-header');
            });
        }
        isClassic = !isClassic;
    });
</script>
</body>
</html>
